The present invention relates generally to radiometric analysis systems and, more particularly, to such systems which utilize liquid scintillators for detecting radiation from radioactive samples.
The use of multiple-sample trays or plates for cell cultures and the like has become commonplace in the field of biotechnology. In many situations, the cell cultures are labeled with radioactive isotopes, and thus the radioactivity of the final samples must be measured. This is often a time-consuming and burdensome process because of the large number of samples involved. For example, in one of the most commonly used multiple-well plates, a total of 96 samples are contained in each plate. Of course, each of these multiple samples must be separately measured.
Systems that have been previously proposed for measuring the radioactivity of such samples typically require multiple steps which render the process time-consuming and, therefore, costly. For example, U.S. Pat. No. 4,298,796 describes a system for measuring the radioactivity of such samples by first removing the samples from the tray or plate in which the cells are cultured, resulting in the transfer of the samples to a filter mat. The filter mat is then enclosed in a container which includes a liquid scintillator, and the individual samples are measured while disposed within the container. The only presently known commercial version of this system utilizes two photomultiplier tubes for detecting the light scintillations attributable to each individual sample, so that the sample can be measured using the well known coincidence detection technique commonly used in liquid scintillation spectrometers.